1. Field of the Invention
The present invention relates to systems and methods for providing a hydraulic drilling sub assembly for use in the excavation, mining and drilling fields. Specifically, the present invention relates to a drilling sub assembly incorporating a hydraulically driven turbine that directly drives a drill bit without the use of gears or other mechanical means to limit the rate of rotation for the drill bit.
2. Background and Related Art
As the world becomes increasingly populated and developed, greater demands are made on the world's supply of natural resources. For example, as technology becomes increasingly accessible and affordable to third-world countries, demands for ground water, natural gas, and petroleum also increase. As a result, greater efforts have been required to recover these natural resources to meet the growing demands of the world's population. To address these challenges, the service industry must develop new technology while improving existing products to provide economical solutions to efficiently tap deep reservoirs of natural resources.
Hydraulic drilling is the process of using turbines to rotate a drill bit. As a drilling fluid is passed over the turbine, the turbine is rotated thereby causing the drill bit to rotate. Typically, a drilling fluid is delivered to the turbine via a string of drill pipes extending from the surface to the turbine. There are many types of drilling fluids including air, air and water, air and polymer, water, water-based mud, oil based mud, and synthetic-based fluid. On a drilling rig, drilling fluid (sometimes referred to as mud) is pumped from mud pits through the drill string where it sprays out of nozzles on the drill bit, cleaning and cooling the drill bit in the process. The mud then carries the crushed or cut rock up the annular space between the drill string and the sides of the hole being drilled. These cuttings are then driven up through the surface case where they emerge back at the surface.
The rate of rotation for the drill bit is commonly controlled by incorporating reducer gears between the turbine and the drill bit. In this way, one can select the speed of the bit by selecting an appropriate gear ratio for a given application. However, several difficulties exist with this method of speed control.
For example, reducer gears are commonly exposed to sediments and other debris found in the drilling fluid. Debris within the drilling fluid can become lodged within the reducer gears causing jams and other malfunctions that must be cleared. The process of clearing these jams are time consuming, expensive and potentially damaging to the drilling equipment. Furthermore, in the event that the drill bit becomes jammed while cutting the rock, the inclusion of reducer gears prevents the drill bit from spinning freely in a direction opposite to the jam. Accordingly, the process of undoing the jam results in downtime and may result in damage to the drill bit and other components of the drilling string.
Thus, while techniques currently exist for hydraulic drilling applications, challenges still exist with such techniques. Accordingly, it would be an improvement in the art to augment or even replace current techniques with other techniques.